Genetic diversity analysis of sorghum genotypes for sustainable genetic resource conservation and its implication for breeding program in ethiopia

Ethiopia is considered to be the center of origin and diversity for sorghum [Sorghum bicolor (L.) Moench]. Knowledge of the genetic structure of the crop is important for its improvement and proper conservation. Therefore, the present study targeted to explore the genetic diversity and population structure of 92 Ethiopian sorghum genotypes representing five populations using 12 polymorphic microsatellite markers. The study resulted in a total of 77 alleles across the entire loci and populations. All the used microsatellite loci were highly polymorphic with PIC ranging from 0.66 to 0.82 with overall mean of 0.76. The analysis confirmed the presence of high within-population diversity with Nei's gene diversity ranging from 0.71 to 0.84 with overall mean of 0.79. Analysis of molecular variance (AMOVA) confirmed high genetic differentiation (FST = 0.29) where 90% of the total genetic variation resides within populations, leaving only 10% among populations. The PCoA, clustering, and population structure did not cluster the studied populations into sharply genetically distinct clusters according to their geographical areas of sampling due to the presence of considerable gene flow (Nm = 2.13). Overall, the used microsatellite loci were highly informative and hence, a useful genetic tool to investigate the genetic structure of sorghum. Among the five studied, populations from North Gondar (Het = 0.75) and South Tigray region (Het = 0.74) showed the highest genetic diversity, and hence these areas could be considered as hot spots for identification of supper-performing genotypes to be used in sorghum breeding program, and also for designing appropriate germplasm conservation strategies.